The temperature, pressure and time dependence of lubricant viscosity

Progress in Ultrasonic Spray Pyrolysis for Condensed Matter Sciences Developed From Ultrasonic Nebulization Theories Since Michael Faraday

“…Viscosity is now known to vary with temperature in a greater than exponential manner and temperature -viscosity equations generally allow for an unbounded viscosity at some characteristic temperature. At high pressure, the pressure-viscosity response is likewise greater than exponential, often following a less exponential response at low pressures [91].…”

“…This was based on the observation of the similarity of viscous flow to diffusion (diffusion coefficient is given by D being ∝ exp(const/T) and also by regarding the flow of molecules past each other as analogous to a chemical reaction (the effect of temperature on the rate of chemical reaction R being also ∝ exp(E/RT) where E is the activation energy). The general form of the pressure [90] and temperature [91] dependence of viscosity has been known for at least 50 years. Viscosity is now known to vary with temperature in a greater than exponential manner and temperature -viscosity equations generally allow for an unbounded viscosity at some characteristic temperature.…”

Two-scale EHL: Three-dimensional topography in tilted-pad bearings

“…Shear-thinning behaviour is modelled using the Ree-Eyring model as originally developed by Johnson and Tevaarwerk [45] and further refined by Bair et al [46], where τ 0 is the Eyring stress and _ γ is the shear rate, Eq. (16) is derived.…”

Friction in Automotive Engines

“…To obtain realistic dynamic lubricant viscosities for the calculations, the viscosities and densities of fresh SAE10/SAE20/SAE30 and SAE40 monograde oils were measured at different temperatures in the OMV-laboratory 4 . To obtain a pressure dependent oil-model for the simulation, the pressure dependency was impressed onto the measured viscosities by applying the well known Barus-equation [5] with the coefficients from [5].…”

“…To obtain a pressure dependent oil-model for the simulation, the pressure dependency was impressed onto the measured viscosities by applying the well known Barus-equation [5] with the coefficients from [5]. The so resulting dynamic viscosities correspond qualitatively to experimental data [4]. Further, a dependence on hydrodynamic pressure was impressed onto the lubricant density following the data found experimentally by Bair et al [4].…”